不同粘结层材料的PS-PVD热障涂层热震性能

Thermal shock performance of PS-PVD thermal barrier coatings with different bond coating materials

为探索不同粘结层材料对等离子喷涂-物理气相沉积(PS-PVD)YSZ陶瓷层的热震性能的影响,采用PS-PVD工艺在DZ40M高温合金上制备了NiCoCrAlYTa和NiCrAlY两种不同的金属粘结层及YSZ陶瓷层,用SEM及XRD等方法表征两种粘结层表面沉积的YSZ陶瓷层的形貌结构、显微硬度及物相,研究了两种涂层的1100℃水淬热震性能及失效模式.结果表明:PS-PVD制备的NiCoCrAlYTa和NiCrAlY两种粘结层均非常致密,陶瓷层均为典型羽毛型柱状结构;NiCoCrAlYTa-7YSZ和NiCrAlY-7YSZ两种羽柱状陶瓷层的孔隙率分别为16.1%和16.5%,显微硬度HV0.025分别为615.8和683.6;陶瓷层的形貌结构及孔隙率、硬度等基本性能,对粘结层成份差异不敏感.1100℃水淬试验结果表明,NiCrAlY-7YSZ涂层的抗热震性能优于NiCoCrAlYTa-7YSZ涂层.失效模式是涂层在频繁的低温-高温热循环中羽柱状陶瓷层内部裂纹萌生和扩展,以及表面花菜头先剥落形成点蚀坑.随着热震次数增加,更多的点蚀坑随机出现并扩大,进而相连后形成大面积剥落区.

In order to explore the influence of different bond coating materials on the thermal shock performance of YSZ ceramic coating prepared by plasma spray-physical vapor deposition(PS-PVD),two different NiCoCrAlYTa and NiCrAlY bond coatings and YSZ ceramic coating were prepared on DZ40M superalloy by PS-PVD process.The bond coating and YSZ ceramic coating were characterized by SEM and XRD.The morphology,microhardness and phase of the YSZ ceramic coating deposited on the surface of the two bond coatings were characterized.The thermal shock performance at 1100℃and failure mode was studied for the two coatings.The results show that the two bond coatings of NiCoCrAlYTa and NiCrAlY prepared by PS-PVD are very dense,and ceramic coatings are typical feather-like columnar structures.The porosity of NiCoCrAlYTa-7YSZ and NiCrAlY-7YSZceramic coatings are 16.1%and 16.5%,respectively.The microhardness HV 0.025 is 615.8 and 683.6,respectively.The coating structure,porosity and hardness of YSZ ceramic are not sensitive to differences in bond-coating composition.The water quenching test at 1100℃showed that the thermal shock resistance of NiCrAlY-7YSZ coating was better than that of NiCoCrAlYTa-7YSZ coating.The failure mode is that during the frequent low-temperature-high temperature thermal cycle,the cracks inside the feather-like columnar structure begin to be generated and expanded,and the surface of the cauliflower head is first peeled off to form pitting pits.As the number of thermal shocks increases,more pitting pits appear randomly and expand,and then connect to form a large-area spalling zone.